Habitat and Morphology of Corynebacterium diphtheriae

Habitat and Morphology of Corynebacterium diphtheriae

Habitat of Corynebacterium diphtheriae Found in nasopharynx as well as in skin lesions, which actually represent a reservoir for the spread of diphtheria. Also found in mouth, throat, nose, skin and wound of infected person. Animals do not easily contract diphtheria. Patients carry toxigenic organism upto 3 months after infection. Morphology of Corynebacterium diphtheriae They are gram +ve rod shaped bacteria. Club …

Read more

Habitat and Morphology of Neisseria gonorrhoeae

Habitat and Morphology of Neisseria gonorrhoeae

Habitat of Neisseria gonorrhoeae Human is only the natural host. Found in human urogenital tract. Rectal carriage in healthy individuals. Typically seen in pus cells (intracellular) Found intracellularly in polymorphonuclear leukocytes, or a specific category of white blood cells with varying shapes of nuclei. Morphology of Neisseria gonorrhoeae Gram –ve cocci Shape is spherical Coffee bean shaped diplococcic Diameter: 0.6 to …

Read more

Habitat and Morphology of Streptococcus pyogenes

Habitat and Morphology of Streptococcus pyogenes

Habitat of Streptococcus pyogenes They are found in throat and skin of human. They are commensals of upper respiratory tract. Carrier rate of S. pyogenes in the respiratory tract is only few in adults, over 10% in children attending kindergarten. Opportunistic pathogens May survive in dust for some times. Morphology of Streptococcus pyogenes Gram +ve bacteria Spherical or oval cocci in …

Read more

Cultural characteristics of Clostridium perfringens

Cultural characteristics of Clostridium perfringens

Cultural characteristics of Clostridium perfringens It is an anaerobic bacteria but can grow under micro-aerophilic condition. They form large, translucent, flat and filamentous colonies with irregular edges. PH: 5.5 to 8.0 (Average PH: 7.2) Temperature: 20°C to 50°C (Average: 37°C) At 45°C, generation time is 10 minutes. Clostridium perfringens on Robertson’s Cooked Meat Broth Saccharolytic species turn meat pink. Meat …

Read more

Habitat and Morphology of Staphylococcus aureus

Habitat and Morphology of Staphylococcus aureus

Habitat and Morphology of Staphylococcus aureus Habitat Natural habitat is mammalian body surfaces. They are normal flora of skin and mucous membrane. Also present in nose / the anterior nares. They can also be found in Pharynx. Found in stratified epithelial cells or mucous or serum constituents associated with these cells. Found in skin/nasal passage and axillae of humans. They …

Read more

Habitat of Clostridium perfringens

Clostridium perfringens

Habitat of Clostridium perfringens Clostridium perfringens are isolated from fecal specimens from human and animals. They are an inhabitant of human normal intestinal flora. They are present in nature and can be found as a normal component of decaying vegetation, marine sediments and soil. Beef, poultry, gravies and dried or pre-cooked foods are common sources of Clostridium perfringens infections. Also …

Read more

Habitat and Morphology of Mycobacterium tuberculosis

Habitat and Morphology of Mycobacterium tuberculosis

Habitat and Morphology of Mycobacterium tuberculosis Habitat Human is only the know reservoir. Usually found in the lungs but can also live in any part of the body. They may be obligate pathogen, facultative or opportunistic pathogens or free living. Usually infect the mono-nuclear phagocytes. Can also be infected by the consumption of unpasteurized milk. Can survive for weeks in …

Read more

Flagella Stain- Principle, Procedure and Result Interpretation

Flagella Stain- Principle, Procedure and Result Interpretation

Objective of Flagella Stain This technique is used to visualize the presence and arrangement of flagella for the presumptive identification of motile bacterial species. Principle of Flagella Stain Flagella are too thin to be visualized using a bright field microscope with ordinary stains, such as the Gram stain, or a simple stain. A wet mount technique is used for staining …

Read more

Spore Stain- Principle, Procedure and Result Interpretation

Spore Stain- Principle, Procedure and Result Interpretation

Members of the anaerobic genera Clostridium and Desulfotomaculum and the aerobic genus Bacillus are examples of organisms that have the capacity to exist either as metabolically active vegetative cells or as highly resistant, metabolically inactive cell types called spores. When environmental conditions become unfavorable for continuing vegetative cellular activities, particularly with the exhaustion of a nutritional carbon source, these cells …

Read more

Capsule Stain- Principle, Procedure and Result Interpretation

A capsule is a gelatinous outer layer that is secreted by the cell and that surrounds and adheres to the cell wall. It is not common to all organisms. Cells that have a heavy capsule are generally virulent and capable of producing disease, since the structure protects bacteria against the normal phagocytic activities of host cells. Chemically, the capsular material …

Read more

Negative Staining- Principle, Procedure and Result Interpretation

Negative Staining- Principle, Procedure and Result Interpretation

Objectives of Negative Staining To perform a negative staining procedure. To understand the benefit obtained from visualizing unstained microorganisms. Principle of Negative Staining Negative staining requires the use of an acidic stain such as India ink or nigrosin. The acidic stain, with its negatively charged chromogen, will not penetrate the cells because of the negative charge on the surface of …

Read more

Simple Staining- Principle, Procedure and Result Interpretation

Simple Staining- Principle, Procedure and Result Interpretation

Objectives of Simple Staining To perform a simple staining procedure. To compare the morphological shapes and arrangements of bacterial cells. Principle of Simple Staining In simple staining, the bacterial smear is stained with a single reagent, which produces a distinctive contrast between the organism and its background. Basic stains with a positively charged chromogen are preferred because bacterial nucleic acids and certain …

Read more

Acridine Orange Stain- Principle, Procedure and Result Interpretation

Acridine Orange Stain- Principle, Procedure and Result Interpretation

Objective Differential staining of nucleic acids including DNA and RNA. Principle Acridine orange, a vital stain, will intercalate with nucleic acid, changing the dye’s optical characteristics so that it will fluoresce bright orange under ultraviolet light. All nucleic acid–containing cells will fluoresce orange. Acridine orange is a metachromatic stain and under appropriate conditions, RNA will stain orange and DNA will …

Read more